Right now none of the "mirrorless" cameras really performs all that well overall. The Nikon 1 series seems to have the best AF, although it still isn't really as good a D3. And of course it's a fairly low resolution sensor with IQ limits that don't satisfy most serious shooters. You can get better IQ with a Sony or Samsung, but again the AF is fairly dismal. The Fuji offerings also have very nice IQ, but handle slowly and are generally clunky. And of course most of the offerings out there have a fairly poor assortment of optics with few genuinely compact lenses that can take advantage of the small size of the cameras themselves.

It's still pretty early in the game to draw any conclusions. The promise is there, but it's still mostly theoretical.